• 한국세라믹학회지
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• 제54권2호
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• pp.108-113
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• 2017

The use of aluminum-based coagulants in water pretreatment is being carefully considered because aluminum exposure is a risk factor for the onset of Alzheimer's disease. Lightly burned-dolomite kiln dust (LB-DKD) was evaluated as an alternative coagulant because it contains high levels of the healthful minerals calcium and magnesium. An organic pore forming agent (OPFA) was incorporated to prepare porous granules after OPFA removal through a thermal decomposition process. A spray drying method was used to produce uniform and reproducible spherical granules with low density, since fine dolomite particles have irregular agglomeration behavior in the hydration reaction. The use of fine dolomite powder and different porosity granules led to a visible color change in raw algae (RA) containing water, from dark green to transparent colorlessness. Also, dolomite powders and granules exhibited a mean removal efficiency of 48.3% in total nitrogen (T-N), a gradual increase in the removal efficiency of total phosphorus (T-P) as granule porosity increased. We demonstrate that porous dolomite granules can improve the settling time and water quality in summer seasons for the emergent treatment of excessive algal blooms in eutrophic water.

• 환경위생공학
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• 제12권3호
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• pp.127-130
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• 1997

The removal of algae was conducted by loess, aluminum sulfate and PAC on a laboratory scale. The loess was consists of organic matter 1.4%, T-N $289{\mu}g/g$, T-P $17{\mu}g/g$, $Al841.2{\mu} g/g$, Fe $592.7{\mu}g/g$, Ca $10.6{\mu}g/g$, Mg $85.5{\mu}g/g$ and Mn $6.6{\mu}g/g$. Test water was dominated by Microcystis aeruginosa. When test water was mixed with 0.01, 0.05. and 0.1 g/$\ell$ of the loess in 5 minutes, after settled in 1 hour, the removal of chl-a was 2, 22, and 36% respectively. The removal of chl-a was 69%, 70% in pH 4.5 and 9.0 and above 92% between pH 5.0 and 8.0 after the $2mg/{\ell}$ of aluminum sulfate was added. When the $2mg/{\ell}$ of PAC and $0.05g/{\ell}$ of loess were added to test water together, the removal of chl-a was 95-99% in pH 4.0-8.0, 60% in pH 9.0, and 18% in pH 10.0. The removal of chl-a was higher when loess, aluminum sulfate and PAC was used together than used alone.

• 한국환경과학회지
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• 제15권3호
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• pp.237-242
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• 2006

The purpose of this research was to investigate the efficiency of coagulants dose after backwashing. The turbidity of initial effluent was high after backwashing in the rapid sand filtration and the high turbidity was almost removed by coagulants dose into filter-sand after backwashing. It was found that the turbidity of initial effluent was well removed by all kinds of the coagulants used in this study. When filtration was performed input water with differentiated pH's, the turbidity of effluent was low at the range of pH 5 - pH 7. But the removal was not good about over pH 9. This result was considered into the existence forms of aluminium, $Al(OH)^{2+}\;and\;{Al(OH)_2}^+$ at pH 5. Cryptosporidiums of effluent were 4/ml for ten minutes immediately after back washing and 3/ml until sixty minutes. However, the case of coagulant dose after backwashing, Cryptosporidiums of effluent were 0.5/ml for ten minutes with no detection after twenty minutes.

• 환경위생공학
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• 제10권1호
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• pp.86-96
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• 1995

Alum recovery has recently gained more attention because many water utilities need to improve their sludge handling and disposal practices. As part of an overall sludge management program recovery can reduce the amount of solids and allow for reuse of the recovered Alum as a coagulant. This study was examined the effectiveness of Alum recovery from the Sludge at the D water treatment plant in Kwangju city. The results were summarized as follows 1. Alum recovery was obtained sufficiently acidification(An optimum condition was pH2-3) With $H_{2}SO_{4}$ to settled sludge. In this case recovered liquid Alum from sludge of 2.1% solids concentration at pH 2.1 was contains Aluminum $1,602mg/{\ell}$(as $Al_{2}O_{3}$ 0.3% ) and other metal of low level. 2. It was an optimum condition to all reuse of recovered Alum as a coagulant that rate of Commercial Alum:Recovered Alum=$14{\mu}{\ell}/{\ell}{\;}:{\;}200{\mu}{\ell}/{\ell}$ In a result of Jar Tests. 3. It was a result of Alum recovery from sludge, the reduction effect of amount of solids was about 57.4%. 4. If all recovered Alum were reused the reduction effect of solid wastes disposal cost and chemical drug's cost was about 22%.

• 상하수도학회지
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• 제30권6호
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• pp.663-671
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• 2016

Coagulation/precipitation process has been widely used for the removal of phosphate within domestic wastewater. Although Fe and Al are typical coagulants used for phosphate removal, these have some shortages such as color problem and low sedimentation velocity. In this study, both Fe and Al were used to overcome the shortages caused by using single one, and anionic polymer coagulant was additionally used to enhance sedimentation velocity of the precipitate formed. Batch experiments using a jar test were conducted with real wastewater, which was an effluent of the second sedimentation tank in domestic wastewater treatment plant. Response Surface Methodology was used to examine the responsibility of each parameter on phosphate removal as well as to optimize the dosage of the three coagulants. Economic analysis was also done on the basis of selling prices of the coagulants in the field. Phosphate removal efficiency of Fe(III) was 30% higher than those of Fe(II). Considering chemical price, optimum dosage for achieving residual phosphate concentration below 0.2 mg/L were determined to be 18.14 mg/L of Fe(III), 2.60 mg/L of Al, and 1.64 mg/L of polymer coagulant.

• 상하수도학회지
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• 제29권2호
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• pp.193-202
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• 2015

The determining the appropriate dosage of coagulant is very important, because dosage of coagulant in the coagulation process for wastewater affects removing the amount of pollutants, cost, and producing sludge amount. Accordingly, in this study, in order to determine the optimal PAC dosage in the coagulation process, CCD (Central composite design) was used to proceed experimental design, and the quadratic regression models were constructed between independent variables (pH, influent turbidity, PAC dosage) and each response variable (Total coliform, E.coli, PSD (Particle size distribution) (< $10{\mu}m$), TP, $PO_4$-P, and $COD_{cr}$) by the RSM (Response surface methodology). Also, Considering the various response variables, the optimum PAC dosage and range were derived. As a result, in order to maximize the removal rate of total coliform and E.coli, the values of independent variables are the pH 6-7, the influent turbidity 100-200 NTU, and the PAC dosage 0.07-0.09 ml/L. For maximizing the removal rate of TP, $PO_4$-P, $COD_{cr}$, and PSD(< $10{\mu}m$), it is required for the pH 9, the influent turbidity 200-250 NTU, and the PAC dosage 0.05-0.065 ml/L. In the case of multiple independent variables, when the desirable removal rate for total coliform, E.coli, TP, and $PO_4$-P is 90-100 % and that for $COD_{cr}$ and PSD(< $10{\mu}m$) is 50-100 %, the required PAC dosage is 0.05-0.07 ml/L in the pH 9 and influent turbidity 200-250 NTU. Thus, if the influent turbidity is high, adjusting pH is more effective way in terms of cost since a small amount of PAC dosage is required.

• 대한환경공학회지
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• 제34권3호
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• pp.149-154
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• 2012

다양한 염기도를 가진 PAC 응집제를 이용한 응집실험에서, 염기도를 낮게 함유하고 있는 PACB (Polymeric Aluminum Chloride Basicity)의 경우 염기도가 높은 PAC 보다 유기물과 인에 응집효율이 높게 나타났다. 저 염기도의 PACB는 고 염기도의 PAC 보다 monomeric Al(III) 가수분해 종을 많이 함유하였다. 하수처리수의 응집에 있어서 전하중화와 sweep floc 형성에 따른 응집효율은 저 염기도의 PACB가 고 염기도의 PAC에 비하여 다소 효과적인 것으로 나타났다. 이에 따라 PACB와 PAC를 이용한 응집실험 결과 $Al_2O_3$ 농도가 유사한 경우 고 염기도의 PAC에 비하여 저 염기도 PACB가 탁도, $COD_{Mn}$ 그리고 TP 및 $PO_4$-P에 대하여 보다 우수한 응집효과를 나타내었다.

• 멤브레인
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• 제25권6호
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• pp.503-514
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• 2015

본 연구는 잔류함으로써 문제를 일으킬 수 있는 응집제를 사용하지 않고 물리적인 처리만을 사용하는 막여과 정수처리의 전처리로 F/A 공정을 구성하고자 하였고 이를 구성하는 여재의 성능을 연구하였다. 특히, 탁질 물질과 유기물 제거가 가능한 것으로 알려진 Filtralite의 도입 가능성을 검토하였다. Filtralite의 탁도 제거효율은 원수대비 83~84%로 여과사와 비슷한 결과 값을 나타내었으며 여재표면에 잘 발달된 공극 때문에 유기물 제거능은 여과사보다 50% 더 높게 나타났다. 따라서 F/A 공정을 구성함에 있어 여과사보다 Filtralite가 더 효율적이라 검토되었다. 활성탄과 연계한 F/A 공정을 구성하여 막여과 처리 시스템의 전처리효율을 실험한 결과, TOC 농도는 TMP의 증가에 큰 영향을 주는 것으로 판단되어 막오염 저감에 유기물 제어가 중요함을 확인하였으며 유기물 제거 효율이 뛰어난 여재 사용이 필요할 것으로 판단되었다.

• 한국환경보건학회지
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• 제38권2호
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• pp.128-135
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• 2012

Objectives: This study was aimed at determining the optimum coagulation dosage in a high turbid kaolin water sample using streaming current detection (SCD) as an alternative to the jar test. Methods: SCD is able to optimize coagulant dosing by titration of negatively charged particles. Kaolin particles were used to mimic highly turbid water ranging from 50 to 600 NTU, and polyaluminum chloride (PAC, 17%) was applied as a titrant and coagulant. The coagulation consisted of rapid stirring (5 min at 140 rpm), reduced stirring (20 min at 70 rpm), and settling (60 min). To confirm the coagulation effect, a jar test was also compared with the SCD titration results. Results: SCD titration of kaolin water samples showed that the dose of PAC increased as the pH rose. However, supernatant turbidity less than 1 NTU after coagulation was not achieved for high turbid water by SCD titration. Instead, a conversion factor was used to calculate the optimum PAC dosage for high turbid water by correlating a jar test result with that from an SCD titration. Using this approach, we were able to successfully achieve less than 1 NTU in treated water. Conclusions: For high turbid water influent in a water treatment plant, particularly during summer, the application of SCD control by applying a conversion factor can be more useful than a jar test due to the rapid calculation of coagulation dosage. Also, the interpolation of converted PAC dose could successfully achieve turbidity in the treated water of less than 1 NTU. This result indicates that an SCD system can be effectively used in a water treatment plant even for high turbid water during the rainy season.

• 상하수도학회지
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• 제32권1호
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• pp.47-53
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• 2018

This study investigated phosphorus removal from secondary treated effluent using coagulation-membrane separation hybrid treatment to satisfy strict regulation in wastewater treatment. The membrane separation process was used to remove suspended phosphorus particles after coagulation/settlement. Membrane separation with $0.2{\mu}m$ pore size of micro filtration membrane could reduce phosphorus concentration to 0.02 mg P/L after coagulation with 1 mg Al/L dose of polyaluminum chloride (PACl). Regardless of coagulant, the residual concentration of phosphorus decreased as the dose increased from 1.5 to 3.5 mg Al/L, while the target concentration of 0.05 mg P/L or less was achieved at 2.5 mg Al/L for the aluminum sulfate (Alum) and 3.5 mg Al/L for PACl. Moreover, alum showed better membrane flux as make bigger particles than PACl. Alum showed a 40% of flux decrease at 2.5 mg Al/L dose, while PACl indicated a 50% decrease of membrane flux even with a higher dose of 3.5 mg Al/L. Thus, alum was more effective coagulant than PACl considering phosphorus removal and membrane flux as well as its dose. Consequently, the coagulation-membrane separation hybrid treatment could be mitigate regulation on phosphorus removal as unsettleable phosphorus particles were effectively removed by membrane after coagulation.